Do you have the Flash player installed for IE? Flash is included with IE in Windows 8.1, but under Windows 7 I don't believe it is even if you've upgraded to IE 11. That said, I would have expected you would be prompted to install Flash instead of getting no video.

Could you post a screen cap of what your display looks like under full screen in Chrome, and note the episode you are playing and the time code? (You'll either have to reduce the size of the screenshot to a maximum of 640 pixels wide, or post a link to it on another site).

I had a different issue with Flash that occurred on the same day, but it was under Firefox and affected sites other than CR. In my case, neither a System Restore (to before a Windows update that same day), re-installing the browser or Flash resolved the issue, but resetting the browser (at the expense of losing some settings and needing to re-install my extensions) did. Chrome also has a reset feature, so if all else fails, that may be the option to go with.

For what it is worth, I installed the latest version of Google Chrome on my system and didn't experience the issue you reported (at least on the one video I tested).

The fact that the video doesn't work at all for him in IE makes me think their is something amiss on his system (given that the Flash installations for Chrome and IE are normally separate binaries), but the fact that he reports only CR as being affected on both, but no one else has reported this issue, points to some type of corruption of settings somewhere.

Another would be set up another Windows user account, log into that, and see if the problem persists. Most settings, cache, etc. would not be carried over to a new account, and it could be deleted once testing was complete.